Conventional letter processing devices suffer from well known processing problems resulting from unique properties of each letter. For instance, letters may have varying formats, unequal thicknesses and different weights. Additionally, letters may be damaged or not glued properly, so that dog-ears stick out. These varying properties cause letter jams, multifeeds, etc., thereby reducing processing times. Also, such problems complicate the transport and especially the singling which is necessary for further processing. Due to these problems, preparatory actions from the emptying of the sacks to the feeding of the stacked and bundled letters are performed manually.
All known measures with which these problems have been addressed up to now have been relatively complex and could only be realized at high costs. Due to the great complexity, such measures are especially accident sensitive, only offer a moderate security, and do not contribute to the amelioration of the tool life.